1. Field of the Invention
The invention relates to mirrors for automotive vehicles. In one aspect, the invention relates to an improved assembly for mounting a mirror actuator jack screw to a mirror carrier for controlling the vertical and horizontal tilt of the mirror. In one embodiment, the invention relates to a slip clutch applied between each jack screw and the mirror carrier to allow slip between these components when the mirror has reached the end of travel but a drive motor continues to run.
2. Description of the Related Art
Rearview mirrors are standard equipment on automotive vehicles. Frequently, the rearview mirrors can be adjusted by the operator from inside the vehicle through a motorized tilt adjustment mechanism, or tilt actuator, mounted within a mirror system. Via a motor, or a pair of motors, the horizontal and vertical tilt of the mirror is controlled by the threaded engagement of an actuator shaft, also called a jack screw, within a drive nut for each of the horizontal and vertical axes.
Frequently, when the actuator shafts reach their limit of movement, the motor will continue to operate for a period of time. The threaded engagement of the jack screw and the drive nut is therefor configured with a “ratchet” mechanism to allow for relative slippage between the jack screw and the drive nut so that the motor can turn without damage to the motor or the jack screw/drive nut assembly. However, this slippage is typically accompanied by a “clicking” sound as the ratchet mechanism is engaged. This clicking sound is frequently interpreted as a performance defect or the result of poor quality, or it can be interpreted as a failure of the actuator, motivating the vehicle owner to seek maintenance that may be unnecessary. Additionally, in mirrors having a positional memory feature for returning the mirror to a preselected orientation for a particular driver, the slippage between the jack screw and the drive nut will disrupt the memory setting, necessitating the resetting of the preselected orientation for each driver using the vehicle.
A clutch mechanism or release mechanism is frequently incorporated into the tilt actuator to accommodate the continued turning of the motor without damage to the motor or the actuator shafts. This slip clutch is typically provided at the base of the actuator shaft, distal from the interconnection of the actuator shaft to the mirror carrier (which carries the mirror element). The actuator shaft is typically mounted to the mirror carrier in a non-rotatable manner. The slip clutch at the base of the actuator shaft can be complex, and generally requires the actuator shafts to be fixedly incorporated into the tilt actuator, thereby restricting their ready removal from the tilt actuator assembly. The complex mechanism adds cost and inhibits the ready installation and removal of the tilt actuator from the mirror system for replacement or repair.